Apparatus for fabricating multi-layer spiral tubes

Abstract

An apparatus for fabricating multi-layer spiral tubes of the type that while the webs are being wrapped in a spiral form the adjacent edge portions of the webs are welded with each other to form spiral tubes, is improved in that the apparatus has a take-up drum for taking up the wrapped webs while rotating with the leading end of the web of the first layer fixedly secured thereto, a wrapping drum having the webs wrapped therearound and including a backing section for backing a welding location of the edge portions of the web of the first layer, a plurality of web feed devices provided adjacent one another for spirally feeding the webs on the wrapping drum of the spiral tubes of the preceding layers, a plurality of wrapping devices provided in combination with the respective web feed devices for spirally wrapping the web on the wrapped drum or the spiral tubes of the preceding layers, and a drawing device for drawing from the wrapping drum the spiral tubes that are being formed continuously.

What is claimed is: 
     
       1. An apparatus for fabricating a multi-layer spiral tube, said apparatus comprising: a rotatable wrapping drum around which a first web forming the innermost layer of the multi-layer spiral tube is spirally wrapped during the fabrication of the multi-layer spiral tube;   a chuck located at one end of said wrapping drum for rotatably supporting said one end of said wrapping drum;   a first drive means operatively connected to said chuck and wrapping drum for rotating said wrapping drum supported by said chuck about an axis of rotation;   a rotatable take-up drum to which the lead edge of the first web is attached, said take-up drum having the same outer diameter as said wrapping drum and having an axis of rotation extending coaxial to said axis of rotation of said wrapping drum;   a second drive means operatively connected to said take-up drum for rotating said take-up drum about said axis of rotation thereof after said innermost layer is attached thereto at the same rate as said first drive means rotates said wrapping drum;   means operatively connected to said rotatable take-up drum for translating said take-up drum in a direction extending along said axis of rotation thereof towards said wrapping drum and away from said wrapping drum after said lead edge of the first web is attached to said take-up drum for advancing the first web spirally wrapped around said wrapping drum for forming the innermost layer of the multi-layer spiral tube;   a first web feed device adjacent said wrapping drum for feeding the first web forming the innermost layer of the multi-layer spiral tube to said wrapping and take-up drums;   a first wrapping device adjacent the outer periphery of said wrapping drum, said first web feed device feeding said first web between said first wrapping device and said outer periphery of said wrapping drum, said first wrapping device comprising   first depressing means for pressing the first web against the outer periphry of said take-up drum, and first attaching means for joining adjacent side edges of the first web spirally wrapped around said wrapping drum;   a second web feed device for feeding a second web corresponding to an outer layer of the multi-layer spiral tube, said second web device spaced from said first web feed device in a direction away from said wrapping drum for feeding the second web on top of and around the first web, after the lead edge of said second web is attached to the innermost layer, in an orientation and direction in which the side edges of the second web do not overlie said adjacent side edges of the first web joined by said first welding means; and   a second wrapping device associated with said second web feed device, the second web feed device feeding said second web between said second wrapping device and the first web formed as the inner most layer on top of which the second web is fed, said second wrapping device comprising   second depressing means for pressing the second web against the innermost layer of the multi-layer spiral tube, and second attaching means for joining adjacent side edges of the second web after it is wrapped around the innermost layer.